package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;
import org.yaml.snakeyaml.events.Event;
import org.yaml.snakeyaml.tokens.Token;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;
import static org.apache.tomcat.jni.Global.unlock;

@Slf4j
@Component
public class CacheChlient {
    private final StringRedisTemplate stringRedisTemplate;
 public void CacheClient(StringRedisTemplate stringRedisTemplate){

 }

    public CacheChlient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time , TimeUnit unit){
     stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicalExpire(String key, Object value, Long time , TimeUnit unit){
     //设置逻辑过期
     RedisData redisDate=new RedisData();
     redisDate.setData(value);
     redisDate.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //写入redis
     stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisDate));
    }
    public <R,ID>R queryWiterPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback,Long time , TimeUnit unit){
        String key=keyPrefix+id;
//从redis查询商铺缓存
        String json=   stringRedisTemplate.opsForValue().get(key);
        //判断是否存在
        if(StrUtil.isNotBlank(json)){

            return JSONUtil.toBean(json,type);
        }
        if(json!=null){
            //返回一个错误信息
            return null;
        }
//不存在，根据id查询数据库
       R r=dbFallback.apply(id);
        //不存在，根据id查询数据库
        if(r==null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            //数据库不存在，返回错误
            return null;
        }

        //存在写入redis
       this.set(key,r,time,unit);
        //返回
        return r;
    }
//解决缓存击穿
private static final ExecutorService CACHE_REBUILD_EXECUTO= Executors.newFixedThreadPool(10);
public <R,ID>R queryWithLogiclExpire(String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, Long time , TimeUnit unit){
    String key=keyPrefix+id;
//从redis查询商铺缓存
    String json=   stringRedisTemplate.opsForValue().get(key);
    //判断是否存在
    if(StrUtil.isBlank(json)){

        return null;
    }
    //命中，需要把JSON反序列化为对象
    //RedisData redisData = JSONUtil.toBean(shopJson.RedisData.class);
    RedisData redisData = JSONUtil.toBean(json, RedisData.class);
   R r=JSONUtil.toBean((JSONObject) redisData.getData(),type);
    LocalDateTime expireTime=redisData.getExpireTime();
    //判断是否过期
if (expireTime.isAfter(LocalDateTime.now())){
    //未过期，直接返回商铺信息
    return r;}

    //已过期，缓存重建
    //获取互斥锁
    String lockKey=LOCK_SHOP_KEY+id;
boolean isLock=tryLock(lockKey);
    //判断获取成功
    if(isLock) {
        //成功，开启独立线程，实现缓存重建
        CACHE_REBUILD_EXECUTO.submit(() -> {
            try {
                //查询数据库
                R r1 = dbFallback.apply(id);
                //写入redis
                this.setWithLogicalExpire(key, r1, time, unit);
            } catch (Exception e) {
                throw new RuntimeException(e);
            } finally {
                unlock(lockKey);
            }
        });
    }
    //返回过期商铺信息

    return r;
}

    //获取锁
    private boolean tryLock(String key){
        Boolean flag= stringRedisTemplate.opsForValue().setIfAbsent(key,"1",10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //释放锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }





}
